A diamond dresser is generally used for dressing of a CBN grindstone. In a precision mass-production grinding field of recent years, a dressing frequency increases in terms of high-precision continuous production, and a reduction in a dressing time is also required to reduce a cycle time. As a result, the diamond dresser has been considered to be problematic in that a lifespan is short and time and a cost is increased. Thus, a technique for improving wear resistance of the diamond dresser to prolong the lifespan has been developed. For example, a rotary diamond dresser in which one crystal plane of an octahedral diamond abrasive grain is embedded to be exposed approximately in parallel to an outer circumference of the dresser with the main intention of improving the wear resistance of the diamond dresser is disclosed in Patent Document 1. In addition, a rotary diamond dresser in which any edge of an octahedral diamond abrasive grain is embedded to be exposed approximately in parallel with a relative rotational velocity vector of a grindstone is disclosed in Patent Document 2. Further, a rotary diamond dresser in which a spiral concave groove is buried and diamond abrasive grains are arranged on a surface excluding the groove at a density of no less than 150 grains/cm2 is disclosed in Patent Document 3.